1. Field of the Invention
The present invention relates to polarized electromagnetic relays, and in particular to such relays having two U-shaped yoke elements disposed parallelly on opposite sides of a permanent magnet with a pivotally mounted armature disposed between opposite angled end legs of the yokes so as to form a working air gap with each of the yoke legs.
2. Description of the Prior Art
A polarized magnet system having two spaced parallel U-shaped yoke elements seated at opposite sides of a permanent magnet is described, for example, in German LP No. 966,845 which is suitable for use as a drive system in relays, alarms, and the like. No specific structure is described therein, however, for permitting a plurality of contacts to be actuated by the armature. Moreover, a separation of the contact space from the coil winding, as is frequently required in relays, is not described in connection with this known structure.
Another known magnet system is described in German OS No. 27 23 430 in which actuation of a plurality of contacts is described as well as a hermetic separation between the coil space and the contact space above the coil is achieved. In this known relay, however, only a single U-shaped yoke proceeds through the coil, the yoke being conducted with two legs in the contact space. This relay can thus be modified for polarized switching only by means of a permanent magnet disposed in the contact space, the permanent magnet being either laterally coupled to the yoke leg ends in an elongated fashion, or being carried by a so-called H-armature. As a result, an effective polarized magnet system with bistable and monostable switching capabilities is possible, however, because of the two ferromagnetic plate elements and one or more permanent magnets disposed therebetween, the H-armature is relatively large and heavy, so that a relatively large mass must be moved during switching. Moreover, the contact space is constricted by the permanent magnet or permanent magnets in the two embodiments disclosed therein.